Figuring out what items are going for on eBay is a tricky process and it's never an exact science. That said, Market Price is a webapp that makes it a little easier to figure out what your item is worth by showing you what it's getting on eBay.

All you need to do is type the item you want to look for into Market Price and it gathers the results from eBay. It then sums up all the info you need to know in a handy graph so you can see what the item is typically going for. Market Price is still in its early stages and the search parameters are simple, but it's incredibly helpful when you're getting ready to sell an item. Combined with searching for "completed listings" on eBay you should be able to get a good idea of what any item you want to sell is going for.